Time- and dose-dependent effect of fosfomycin on suppression of infection-induced endotoxin shock in mice

Therapeutic effects of fosfomycin (FOF) and imipenem (IPM) were investigated in a novel model for endotoxin shock that was caused by intraperitoneal (i.p.) infection with 10(8) colony forming units of attenuated Salmonella typhimurium. Acute lethal shock was observed in BALB/c and ddY but not in lipopolysaccharide (LPS)-nonresponder BALB/lps(d) mice. Effects of FOF, but not its enantiomer, and IPM were dose- and time-dependent, since therapeutic efficacy was demonstrated in mice injected i.p. or orally at doses of more than 20 mg/kg 15 min before or 1 h after infection. Treatment with FOF 1 h postinfection (p.i.) resulted in significant decreases in bacterial numbers in spleen and liver, suggesting that the antimicrobial activity of FOF seems to closely correlate to suppression of infection-induced lethal shock. Regarding coagulation systems, FOF inhibited increase in the prothrombin time but upregulated fibrinogen concentration. Plasma levels of LPS released from bacilli were significantly higher in FOF- than IPM-treated mice and infection controls, but both antibiotics showed similar efficacy in protection.